Oven and microwave on same 30A oven ckt?

[bullheimer]

searched and no posts with ovens in the title so...

nothing says you can't put an oven and a cooktop on the same circuit. i know you can put an oven and a cooktop on a 50A circuit, but those two take alot of juice. i have this customer that bought a 240V microwave that takes 15A. the oven says it takes 17. i know that is 32A because i can do simple addition, and i know 10g wire is good for at least 35A. i also know i can't fuse the 10g at more than 30A.

WHAT says i can't supply them both from the same circuit? are they continuous loads? is there no reductioins, like with multiple ranges or dryers? i am sure there is something that wont let me do it, and am planning on running a new 240 ckt tomorrow. (the stupid micro requires a neutral!).

the reason is the customer told me to run a 20A 120 for the micro above the 30A oven outlet, which i did. but it is of no use now since fool customer went out and got this 240V micro. it is NOT a Bosch, which lets you feed one from the other, either. they are both kitchen aid. and dig this: Kitchen Aide (whirlpool) factory HAS NO, ZERO, TECH SUPPORT!!!!!:thumbsdown: all they have is NO instructions for this with the micro, but the oven DID have instructions saying to put it on it's own circuit breaker.

 

[broadgage]

In practice it should work fine, and be safe, but I feel that it would a violation on at least two counts.

Firstly the instructions with the microwave say to put it on its own circuit, and not following this instruction is probably a violation.

Secondly, for what maximum OCPD is the microwave listed ? Almost certainly less than 30 amps I suspect. Probably 15 or 20 amps, in which case connecting an appliance to a larger OCPD than specified is likely a violation.

Does the microwave oven actually USE 15 amps ? or is it designed for a 15 amp circuit ? with an actual current draw of less than 15 amps.
15 amps at 240 volts is an awfull lot for a microwave oven ! very large ones in the UK seldom exceed 13 amps at 240 volts.

If it does actually use a full 15 amps, then the total load on the branch circuit is more than 30 amps. I would not consider either appliance to be a continous load, so the branch circuit can be loaded to 100%, but in this case the load is more than 100 %

Should be fine in practice, but strictly correct ? I think not.

 

[Smart $]

FWIW a cooktop and oven combination under code are assuming they are both built-in units, essentially amounting to the load equivalent of one freestanding range.

Is the microwave a countertop appliance or built-in unit?

If the microwave is cord-and-plug connected, you will likely be limited to a circuit rating not higher than the matching receptacle rating... and as mentioned, you cannot knowingly put a greater load on the circuit than what it is rated.

 

[cpinetree]

It always amazes us that kitchen remodels NEVER seem to have the correct appliance and cabinet details when roughing them in, and then its up to us, the electrician to redo all of our work often at a reduced cost because of their failure to communicate the changes.

:rant:The thing that drives me the most crazy is that the customers will spend $2,000 on microwave convection oven and then whine and moan about the $300 to run the circuit and hook it up.:rant:

Lately when estimating kitchen remodels we are very specific that it is an estimate and the job will be billed at time and material, because there are so many additions, changes, hidden factors, extra trips, things not ready when we are told to be there etc.

It is very easy to overrun a $2000 kitchen electric rewire / remodel by $1000, by the time it is done, and that is still less than they paid for the crappy refrigerator.:weeping:

 

[kwired]

My thoughts are that since you said you ran a dedicated 20 amp (120 volt) circuit already, why not just change that circuit to a 240 volt circuit and use it?

 

[cpinetree]

My thoughts are that since you said you ran a dedicated 20 amp (120 volt) circuit already, why not just change that circuit to a 240 volt circuit and use it?

most of them require 4 wire. Not like the ovens and cooktops that can be wire 3 or 4 wire.

 

[kwired]

most of them require 4 wire. Not like the ovens and cooktops that can be wire 3 or 4 wire.

Well he said it was 240 volt, if he would have said it was 120/240 volt that would have clarified things a lot. I have never seen such a unit, so I do not know what the "norm" is.

 

[PetrosA]

It always amazes us that kitchen remodels NEVER seem to have the correct appliance and cabinet details when roughing them in, and then its up to us, the electrician to redo all of our work often at a reduced cost because of their failure to communicate the changes.

:rant:The thing that drives me the most crazy is that the customers will spend $2,000 on microwave convection oven and then whine and moan about the $300 to run the circuit and hook it up.:rant:

Lately when estimating kitchen remodels we are very specific that it is an estimate and the job will be billed at time and material, because there are so many additions, changes, hidden factors, extra trips, things not ready when we are told to be there etc.

It is very easy to overrun a $2000 kitchen electric rewire / remodel by $1000, by the time it is done, and that is still less than they paid for the crappy refrigerator.:weeping:

$2000 for a kitchen remodel? That sounds VERY barebones... Last large kitchen I did cost about the same as their range I can't even imagine doing a small kitchen for that price unless hardly anything is changing.

 

[kwired]

Last large kitchen I did cost about the same as their range

That doesn't help get your point across IMO, you can get a range for as little as a couple hundred dollars or spend ten thousand or even more in some instances maybe.

Add: I haven't went looking at ranges at the consignment stores for years now but you used to be able to get one for maybe only twenty bucks, but it was definitely not the latest in style.

 

[cpinetree]

$2000 for a kitchen remodel? That sounds VERY barebones... Last large kitchen I did cost about the same as their range I can't even imagine doing a small kitchen for that price unless hardly anything is changing.

These are not large kitchens or homes most built in the 70's + 80's under 2000 sq ft. Usually new cabinets, change and add some recpts, recess can or 2 etc
They can be roughed by 1 guy in a day or less and trimmed in 1 day or less if things are complete and ready :lol:

 

[dereckbc]

We do not have enough information to answer the question directly.

For demonstration purposes let's assume it complies. If this were your home would you do that? I know I would not as that would be a poor practice and asking for trouble.

 

[kwired]

These are not large kitchens or homes most built in the 70's + 80's under 2000 sq ft. Usually new cabinets, change and add some recpts, recess can or 2 etc
They can be roughed by 1 guy in a day or less and trimmed in 1 day or less if things are complete and ready :lol:

Still, unless there is hardly any cabinets at all even some really cheap ones will eat up most of 2 grand in cabinets alone - and they are often replacing countertops and sink as well. Whoever is doing this probably wants a little labor on top of it even if he is cheap.

 

[cpinetree]

Still, unless there is hardly any cabinets at all even some really cheap ones will eat up most of 2 grand in cabinets alone - and they are often replacing countertops and sink as well. Whoever is doing this probably wants a little labor on top of it even if he is cheap.

That is just the electric, my point was the customers spend more for a single appliance than for all of the electrical including the permit.

 

[bullheimer]

thanks for the replies. the microwave has to be hard wired as there is a whip with four wires in it, they look to be 14g at best. i am pretty amazed that it will draw 15 amps (it says it uses 3600 watts) at 240, so.....i guess that would get around any load/recept issues. also the oven has a whip as well with i believe 12g wires

if it were my house, i don't know, i guess i would wire it up and do an actual voltage draw on it first. i expect it to be less, but then maybe the oven, if i did the same, would be more, don't have any 240 extention cords laying around. but i guess maybe that is the only way.

btw this is a new house w/a change order. attic above is accessible, i left a 1"pipe from the panel to the attic so it's very doable. just that it's already had 20" of fluff blown in. i tend to run a pipe to the attic in every new house i do, just in case! make sure to use a cap or duct seal.

also broadbase, it was the oven that said it should be on it's own ckt, not the micro, but it makes no difference. but then, check this out, in the ovens directions it says it can share a circuit with an list of cooktops! so... what does THAT mean? And in that note it does NOT say what the size of that ckt must be!! and after two calls to kitchen aid, to get the BS that they have NO TECH support for me, really just sent me off the deep end. i cussed out both of the two gals who gave me lip that i wasn't allowed to call their tech line unless i was a certified installer. well, happy thanksgiving beaches!

 

[Smart $]

thanks for the replies. the microwave has to be hard wired as there is a whip with four wires in it, they look to be 14g at best. i am pretty amazed that it will draw 15 amps (it says it uses 3600 watts) at 240, so.....i guess that would get around any load/recept issues. also the oven has a whip as well with i believe 12g wires

...

The 14ga whip conductors rules out feeding from same circuit as oven. The only permitted tapping of a household cooking appliance circuit requires 20A conductors, including whip conductors, and the circuit must be rated 50A. See 210.19(A)(3) Exception No. 1.

 

[kwired]

thanks for the replies. the microwave has to be hard wired as there is a whip with four wires in it, they look to be 14g at best. i am pretty amazed that it will draw 15 amps (it says it uses 3600 watts) at 240, so.....i guess that would get around any load/recept issues. also the oven has a whip as well with i believe 12g wires

if it were my house, i don't know, i guess i would wire it up and do an actual voltage draw on it first. i expect it to be less, but then maybe the oven, if i did the same, would be more, don't have any 240 extention cords laying around. but i guess maybe that is the only way.

Is this a microwave only? My guess is it is more likely a "speedcook oven" that has

Airspeed Technology circulates currents of heated air from the top and bottom of the oven cavity to brown, sear and caramelize food. Precision microwave assists when helpful in the cooking process

The toaster ovens in Subway sandwich shops, and many other rather fast baked foods in restaurants are done in this kind of oven these days, it is a fan forced oven with assistance from microwave action also and can cook foods up to 15 times faster than a conventional oven according to TurboChef.

 

[bullheimer]

yeah, the factory installer guy who sold my guy his stuff said it needs a dedicated 20A ckt. the end...

it's called, according to him, a microwave convection oven. same diff as your speed cook i'm guessin.

funny thing, it just never ends. the hole in the cabinets for the two of them is only 34 inches, and the oven is 27, the micro above it is 17. do the math, then break out your sawzall. now where's the smiley face slappin hisself upside the head??

 

[GoldDigger]

... now where's the smiley face slappin hisself upside the head??

Right here....
:slaphead:

 

[SMARTERCARTER]

None of these answers were very helpfull sooooo-

Here is what you do if you are a real Electrician.

*Using my 2011 Handbook (Check current code book but i doubt this has changed) Comment below if it has.

Look at *220.55 Note #4 and Note #5- note the phrase "household cooking appliances" not just "Ovens" and "cook tops" there is no hard definition that excludes micro. its states you can supply a cook top and two ovens max with one circuit . Period ! IT will be added together and the KW total will be seen as ONE range and then use your chart Column A B or C. Table 220.55.
SO NOTE 5= Microwave is a Household cooking appliance as well as it is a combo convection oven anyway which takes precedence anyhow.

the neutral load will be more than usual on the Micro wave but similar since the code compensates for the neutral by keeping it 30 amp min. and romex is full size N who cares !
So that's plenty for the micro and any low stetting oven neutral loads... as some ovens do apply a neutral load to the circuit in low setting apparently ...i did not know that .! Nor did i care since most feeder cables ran have a full size neutral. But some old houses may not have...

For example if you have 2 -3000 kw appliances then you go with =6000 @25 amps and the demand of 2 @ Column B is 65 %.(16.25amps) of that total could be used for sizing. feeder. and Breaker so a 20amp 240 volt circuit could handle all that ! Coool! Always run the neutral You never know what is coming out to the job or what could happen in the future if some decide to change it. IF I were doing it I would run 8/3 anyway and run the breaker at 30 maybe in the hypo above but you can do 20 and 20 amp wire if you want. Wire is a heat sink so you take more of a chance of burning up something like a wire nut or terminal connection if you use small wire. so think safety but dont over do it too much is my opinion.

*ARTICLE 210 .19 (A) 3 states that any appliance shall have an ampacity **(not less than) the rating of the branch circuit and not less that is the maximum load to be served.

*210 .19 (A) 3. Exception #1 talks about tap conductors being not less than 20 amp wire.... this can count for appliance conductors from factory and your flex whip if you need one to go from j box to micro or cook top . so those could be 20 amp min. but again size with your heat sink in mind ...don't always do the min required . if you get a loose connection it may save you if you have bigger wire. and 20 amp and 50 dont mix well either in a wire nut... seen those catch fire. two similar size wires twist better or use insulated lugs for a sure connection for two different size wires.

Neutral can not be ampacity of not less than 70 percent of branch circuit rating and not less than # 10= Exception #2

**so breaker maximum is not noted if you notice... any breaker will protect from a short ... the worry with an oven is a short not an overload since the element can only do so much. and people don't turn everything on and blast it for 3 hours at a time! Common sense is needed too here. its not like they are firing swords in there oven !!! cooking a turkey in the convection all day etc....if they do they deserve to have their house burn down ..LOL


Your Welcome!

 

[SMARTERCARTER]

yeah, the factory installer guy who sold my guy his stuff said it needs a dedicated 20A ckt. the end...

it's called, according to him, a microwave convection oven. same diff as your speed cook i'm guessin.

funny thing, it just never ends. the hole in the cabinets for the two of them is only 34 inches, and the oven is 27, the micro above it is 17. do the math, then break out your sawzall. now where's the smiley face slappin hisself upside the head??

HE is wrong! Never Go by the "factory installer guy" said... NEC is what you go by. They just cover . . . . (Moderator's Note: inappropriate language removed.)